The present invention relates to a device for piercing holes in rod-shaped items.
The present invention is particularly suitable for producing smoking commodities, especially cigarettes, to which the following description refers solely by way of a non-limiting example.
The cigarette manufacturing industry is known to produce so-called "ventilated" cigarettes, i.e. cigarettes with a number of holes in the area of the filter. This enables smokers to inhale a certain amount of air together with the smoke, in such a manner as to dilute the smoke intake and reduce both its temperature and content of harmful substances.
The ventilating holes are known to be formed using piercing devices comprising a laser source, possibly pulsating, and a focusing device designed to direct the laser beam on to the cigarettes as they travel along a given route, possibly also turning round their own axes.
On the aforementioned known types of piercing devices, the focusing device is usually assigned a reflecting member designed to direct the focused beams on to the cigarettes in such a manner as to follow them as they are moved along.
One of the major drawbacks of piercing devices of the aforementioned type is that the holes so formed are usually irregular in shape and unevenly arranged round the cigarettes. The main reason for this is that the laser source, the focusing device and the associated reflecting member are generally located some distance away from the cigarettes being pierced. The movement of the cigarettes along the given route is determined by a conveying device supported separately from the respective piercing device. As the piercing device is thus unaffected by the vibration usually imparted on the cigarettes by the conveying device, the cigarettes being pierced depart unpredictably from what should be a given ideal route.